【作者】 徐慧；

【导师】 成杰民；

【作者基本信息】 山东师范大学 ， 环境科学， 2010， 硕士

【摘要】 多环芳烃(polycyclic aromatic hydrocbarons,PAHs)是指含有两个或两个以上苯环,以线状、角状或簇状排列的稠环型化合物。具有难降解性、持久性和“三致”作用,其环境行为、归趋及风险评估越来越受到人们的重视。准确有效的评价多环芳烃的生物有效性是进行风险评价的重要环节。本论文通过室内模拟的方法对土壤中多环芳烃的去除机制进行了初步研究;通过选择一系列的敏感指标,包括蚯蚓、小麦和土壤酶等,对不同污染程度的性质不同的土壤进行了毒性评价,通过不同生物之间和不同指标之间的比较,找出了较敏感的生物指标;分别用羟丙-β-环糊精(hydroxypropyl-β-cyclodextrin,HPCD)和丙酮二氯甲烷对老化时间不同的土壤中多环芳烃生物有效性和总量进行了评价和比较,研究了老化对多环芳烃可提取性和生物有效性的影响。本论文的主要研究结果如下:土壤中多环芳烃的去除途径主要有挥发、生物降解、非生物降解等。土壤中菲和芘都是以微生物降解为主,其次是挥发、化学降解等非生物降解方式。菲的微生物降解、挥发易于芘。菲的HPCD提取态高于芘的HPCD提取态,也说明菲的微生物降解强于芘。土壤有机质含量和多环芳烃自身性质是其去除途径不同的主要影响因素。本论文中选择了不同生物种类的不同指标,包括蚯蚓死亡率和体内抗氧化酶、小麦的种子发芽率、芽长、根伸长、芽鲜重、根鲜重、根和芽中抗氧化酶、土壤酶活性。对于未老化的土壤来说,蚯蚓死亡率、小麦的种子发芽率、芽长、根伸长、芽鲜重、根鲜重是高浓度污染土壤(菲200mg·kg-1+芘200mg·kg-1)的敏感指标,对于低浓度污染土壤(菲2mg·kg-1+芘2mg·kg-1)这些指标不敏感,为了对其毒性准确评价,对蚯蚓、根和芽中抗氧化酶指标(超氧化物歧化酶、过氧化氢酶、丙二醛、蛋白质)进行了测定。对于蚯蚓、小麦芽、小麦根来说SOD都是最敏感指标,其次为CAT、MDA、蛋白质含量。对于老化30天的土壤来说,蚯蚓死亡率、小麦的种子发芽率、芽长、根伸长、芽鲜重、根鲜重不再是高浓度污染土壤(菲200mg·kg-1+芘200mg·kg-1)的敏感指标,蚯蚓、根和芽中抗氧化酶指标中SOD是敏感指标。三种土壤中菲和芘总量都随着时间的延长而降低,降低速率上呈现出先快后慢的特点。菲下降的程度要高于芘。红壤中总量的浓度最高,黄棕壤次之,黑土最低,与三种土壤中有机质含量大小有关;三种土壤中菲和芘HPCD提取态都随着时间的延长而降低,降低速率呈现出先快后慢的特点。菲下降的程度高于芘。红壤中HPCD提取态最高,黄棕壤次之,黑土最低;三种土壤中菲和芘的总量都明显高于HPCD提取态,从提取效率上看,红壤最高,黄棕壤次之,黑土最低,且菲的提取效率高于芘。所以在对污染场地进行风险评价时,应选择合适的浓度标准,这样才能准确的评估风险大小。更多还原

【Abstract】 Polycyclic aromatic hydrocbarons are a unique class of pollutants which are constituted by hundreds of individual substances.These compunds contain two or more fused aromactic rings made up of carbon and hydrogen atoms.The behaviors and fates of PAHs are of increasing concern,on account of their non-degradation、persisence and carcinogenic、tumorigenic and mutagenic properties of certain of them.Assessing the availability of polycyclic aromatic hydrocbarons accurately and effectively in soil is important for risk assessments.Preliminary studies on the removal mechanism of polycyclic aromatic hydrocbarons in soil were made by laboratory simulation study;The toxicity for the soil contaminated by polycyclic aromatic hydrocbarons was evaluated by biological indicators,including earthworm,wheat and soil enzyme activity.Comparing of the different results of the indicators,the more sensitive indicators were choosen.Total polycyclic aromatic hydrocbarons content was determined by dichloromethane extraction.The bioavailability of polycyclic aromatic hydrocbarons was determined by hydroxypropyl-β-cyclodextrin.Large difference was observed between the two methods.The effects of aging on total PAHs content and bioavailability fraction were analyed.The main results are as follows:The removal pathway of polycyclic aromatic hydrocbarons in soil includes volatilization、biodegradation and abiotic degradation. Phenanthrene and pyrene in soil are based on microbial degradation, followed by abiotic degradation such as volatilization, chemical degradation. Microbial degradation and volatilization of phenanthrene are easier than pyrene. The amount of phenanthrene extracted by the means of HPCD was always higher than pyrene, so phenanthrene was more readily available than pyrene.Soil organic matter content and the nature of polycyclic aromatic hydrocbarons are the main influence factors .The paper chose a series of different indicators, including earthworm mortality, antioxidative enzyme activity, wheat seed germination, shoot length, root elongation, shoot fresh weight, and root fresh weight, antioxidant enzyme activity in root and shoot, soil enzyme activity. With the soil not aged, earthworm mortality, wheat seed germination, shoot length, root elongation, shoot fresh weight, root fresh weight were sensitive for the high concentration of contaminated soil (phenanthrene 200mg?kg-1 + pyrene 200mg?kg-1) ,but not for the low concentration of contaminated soil (phenanthrene 2mg ? kg-1 + pyrene 2mg ? kg-1).In order to accurately evaluated their toxicity,antioxidant enzyme activity in earthworms, roots and shoots of wheat( superoxide dismutase, catalase, malondialdehyde, protein) were measured. SOD is the most sensitive indicators, followed by CAT, MDA, protein content.With the soil aged for 30 days, earthworm mortality, wheat seed germination, shoot length, root elongation, shoot fresh weight, root fresh weight are no longer sensitive for high concentration (phenanthrene 200mg?kg-1+pyrene 200mg ?kg-1), antioxidant enzymes activity in earthworms, root and shoot of wheat were measured, SOD was the most sensitive indicator.Total PAHs content decreased as the time extended, and the rate was rather high at the initial stage, and then slowed down in the rest of time. The degree of decline in the phenanthrene than pyrene.Red soil had the highest concentration, yellow brown second, and black the lowest, proportional to the soil organic matter content soil.The amount of phenanthrene and pyrene extracted by the means of HPCD decreased as the time extended, and the rate was rather high at the initial stage, and then slowed down in the rest of time. The degrees of decline in the phenanthrene than pyrene.Red soil had the highest concentration, yellow brown second, and black the lowest. The total amount of phenanthrene and pyrene were significantly higher than the amount of phenanthrene and pyrene extracted by the means of HPCD. From the extraction efficiency point of view, red highest, yellow brown second, and black the lowest, and phenanthrene higher than pyrene. Therefore,we should select the appropriate extraction methods, so as to assess the risk accurately.更多还原